Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/02—Homopolymers or copolymers of hydrocarbons
  • C08L25/04—Homopolymers or copolymers of styrene
  • C08L25/08—Copolymers of styrene
  • C08L25/12—Copolymers of styrene with unsaturated nitriles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L55/00—Compositions of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08L23/00 - C08L53/00
  • C08L55/02—ABS [Acrylonitrile-Butadiene-Styrene] polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons

Definitions

• the invention relates to a process for the preparation of a thermoplastic moulding composition with low surface gloss on the basis of a graft copolymer of a vinyl aromatic compound, and optionally an acrylic compound, on a rubber, and optionally a copolymer of a vinyl aromatic compound and an acrylic compound.
• ABS plastics One of the characteristic properties of ABS plastics is, besides the good impact strength, the attractive, glossy surface.
• Examples of such applications are housings of electrical equipment, cases and automotive parts such as dash boards.
• the object of the invention is to provide a simple process by which ABS plastics having low surface gloss can be made.
• the process according to the invention is characterized in that a latex of the graft copolymer and/or the copolymer is mixed with latex of a rubber and the mixture obtained is coagulated and further processed in a way known per se.
• the rubber latex to be added preferably is a latex of a rubber corresponding to the rubber in the graft copolymer. This has as an advantage that the application of special additives, such as antioxidants, for the rubber applied can usually be dispensed with.
• the final product also contains the rubber which is incorporated in the graft copolymer.
• the grafted rubber usually is 5-40 wt. % of the graft copolymer and the copolymer component of the final product taken together.
• the graft copolymer can be obtained by emulsion polymerization of one or more vinyl aromatic compounds, and optionally an acrylic compound, in the presence of a rubber.
• the preparation of the graft copolymer and/or the copolymer should at least in part take place by means of emulsion polymerization. Another possibility is that the graft polymer and/or the copolymer is brought into latex at a later stage.
• the other component which is then added after the coagulation of the latex mixture, for instance in the extruder, may be prepared via the same or a different polymerization method. It is, of course, essential that an amount of graft copolymer is present in the ultimate moulding compound.
• vinyl aromatic compound styrene, a-methyl styrene or derivatives of these compounds that are substituted in the aromatic ring are suitable in the preparation of the (graft) copolymer.
• Suitable derivatives are alkyl groups such as a methyl group and/or halogens such as chlorine or bromine. Also, mixtures of two or more vinyl aromatic compounds can be applied.
• one or more other monomers can be used in the preparation of the graft copolymer and/or the copolymer.
• acrylic compounds such as acrylonitrile and methacrylonitrile
• acrylates such as methylmethacrylate or ethylacrylate.
• Possible other suitable monomers are maleic anhydride, coumarone, indene and vinyl acetate.
• the graft copolymer and the copolymer optionally used are preferably built up of the same monomers. It is, however, also possible to prepare the graft copolymer with styrene and acrylonitrile as monomers, while in the copolymer styrene and/or acrylonitrile are partly or wholly replaced by one or more other monomers such as methylmethacrylate, a-methylstyrene or maleic anhydride.
• any rubber may be applied in the preparation of the graft copolymer. It is preferred to use polybutadiene homopolymers or butadiene copolymers having a butadiene content of more than 60 wt. %. If other dienes, for instance isoprene, or the lower (C 1 -C 4 ) alkyl esters of acrylic acid, are used as comonomers, the butadiene content of the rubber can be reduced to 30 wt. % without any disadvantage with respect to the properties of the polymer composition.
• the graft polymer according to the invention from saturated rubbers, for instance from ethylene vinyl acetate copolymers with a vinyl acetate content of less than 50 wt. % or from ethylene-propylene-diene-terpolymers (these dienes are not conjugated; examples are 1,4 hexadiene, ethylidene norbornene, dicyclopentadiene), as well as from acrylate rubber, chlorinated polyethylene or chloroprene rubber. Mixtures of two or more rubbers can also be applied.
• auxiliary materials such as chain length regulators, emulsifying agents (emulsion polymerization) and compounds supplying free radicals.
• Suitable chain length regulators are organosulphur compounds such as the often used mercaptans as well as the dialkyldixantogens, diarylsulphides mercaptothiazoles, tetra-alkyl thiurammono- and disulphides, etc.,.separately or mixed with each other, as well as hydroxyl compounds such as terpinolenes.
• the dimer of a-methylstyrene or an a-alkene having a relatively long chain can be used.
• chain length regulators are especially the mercapto compounds and of these it are the hydrocarbyl mercaptans with 8-20 carbon atoms per molecule that are much used currently. More in particular preference is given to mercaptans with a tertiary alkyl group.
• the amount of organosulphur compound may vary within wide limits, depending on the mixture chosen, the specific compound, polymerization in temperature, emulsifying agent and other variables relating to the formulation.
• a good result can be obtained by using 0.01-5 parts by weight (per 100 parts by weight of monomer) of organosulphur compound, preference being given to 0.05-2 parts.
• Suitable organosulphur compounds comprise n-octyl mercaptan, n-dodecyl mercaptan, tertiary dodecyl mercaptan, tertiary nonyl mercaptan, tertiary hexadecyl mercaptan, tertiary octadecyl mercaptan, tertiary eicosyl mercaptan, secondary octylmercaptan, secondary tridecyl mercaptan, cyclododecyl mercaptan, cyclododecadienyl mercaptan, aryl mercaptan such as 1-naphtalenethiol, etc., bis-(tetramethylthiuramdisulphide), 2-mercaptobenzathiazol, et cetera. Mixtures of these compounds can also be used.
• emulsifying agent widely different compounds can be used, such as disproportionated resin soap, fatty acid soap, mixtures of these compounds, arylsulphonates, alkylarylsulphonates and other surface- active compounds and mixtures thereof.
• Nonionogenic emulsifying agents may also be used, such as polyethers and polyols. The amounts of emulsifying agents used are dependent on the type as well as on the reaction parameters and the concentrations of polymerizable monomer in the emulsion polymerization system.
• Suitable compounds supplying free radicals for the emulsion polymerization process are organic or inorganic peroxides, hydroperoxides, azo compounds as well as redox initiator systems. These compounds can be added at the start of the polymerization. It is also possible to add part of these compounds at the start and part in the course of the polymerization.
• alkali or ammonium persalts and/or redox systems are chosen as initiators.
• potassium persulphate ammonium persulphate and sodium persulphate.
• exemplary of suitable redox systems are persalts (for instance perchlorates or persulphates), tertiary butylhydroperoxide, cumenehydroperoxide, diisopropylbenzenehydroperoxide and methylcyclohexylhydroperoxide, combined with reducing agents on the basis of acids containing sulphur in a low valence condition, such as sodium formaldehydesulphoxilate, bisulphide, pyrosulphide, or with organic basis such as triethanolamine, with dextrose, sodium pyrophosphate and mercaptans or combinations thereof, optionally in combination with metal salts such as ferrosulphate.
• These initiators or initiator systems may be added in one charge, step-wise or even gradually.
• the rubber to be added preferably is a butadiene rubber. Suitable rubbers are polybutadiene, styrene-butadiene rubber or butadiene acrylonitrile rubber. More in particular the polybutadiene and styrene-butadiene rubbers are preferred. As already indicated above, it is essential that the rubber be mixed in latex form with the graft and/or copolymer. For this reason the rubber will preferably be prepared by an emulsion polymerization process. To this end the auxiliary materials indicated herein before for the preparation of both the rubber and the graft copolymer can be used.
• the average particle size of the rubber to be added preferably is between 0.05 and 1.5 pm (d 50 on a weight basis). This size gives a good result as regards low surface gloss. In particular an average particle size in excess of 0.5 ⁇ m is preferred.
• Mixing of the two or more latices can be effected in various ways. Examples are mixing in a static mixer, in an in-line mixer, or in a simple stirred vessel, into which the latices are introduced. It is of importance that the latices do not, or in any case not to any substantial degree, coagulate during mixing as otherwise problems may arise with the surface and mechanical properties of the final product.
• the mixture is coagulated in a conventional way. This is usually done by adding a salt or an acid to the latex. Suitable compounds are sulphuric acid, calcium-chloride or magnesium sulphate.
• the slurry obtained can be dewatered and washed, so that after drying a powder is obtained.
• This powder may then be mixed in an extruder with various auxiliary materials such as pigment, lubricant, antioxidant, antistatic agent, et cetera, after which the mixture is granulated or processed directly into products.
• auxiliary materials such as pigment, lubricant, antioxidant, antistatic agent, et cetera
• one or more other plastics may also be mixed with the graft copolymer and the rubber.
• the graft copolymer in the preparation of ABS, for instance, it is common practice to mix the graft copolymer with a copolymer of a vinyl aromatic compound and an acrylic compound (for instance SAN) to reduce or uniformize the content of grafted rubber in the eventual moulding compound.
• an acrylic compound for instance SAN
• This copolymer can be added in said extruder.
• the copolymer is available as latex, there may be advantage in mixing the latex of the copolymer with the latex of the graft copolymer.
• an ABS product can be obtained which combines low surface gloss with good mechanical properties.
• these products have the advantage that the gloss does not increase on heating.
• the conventional mat products in part of or wholly become glossy again on further processing (vacuum forming).
• the mixed latex was coagulated with sulphuric acid at 93°C.
• the powder obtained was centrifuged off, washed out and dried to a moisture content of ⁇ 1 wt. X.
• the resultant polymer mixture was subsequently mixed with a styrene-acrylonitrile copolymer (styrene/acrylonitrile ratio 70/30).
• the mixture obtained was subsequently coagulated with sulphuric acid at 95 °C, on which the powder was centrifuged off, washed out and dried.
• Example 2 The procedure of Example 1 was repeated, however without the addition of SBR-latex. After coagulating, drying and extruding to a strip, the properties were as follows:

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Graft Or Block Polymers (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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Cited By (3)

Citations (4)

• 1982
  • 1982-05-07 NL NL8201893A patent/NL8201893A/nl not_active Application Discontinuation
• 1983
  • 1983-05-06 DE DE8383200645T patent/DE3363021D1/de not_active Expired
  • 1983-05-06 AT AT83200645T patent/ATE19259T1/de not_active IP Right Cessation
  • 1983-05-06 EP EP83200645A patent/EP0094135B1/fr not_active Expired

Patent Citations (4)

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